A photoelectric conversion element such as a photovoltaic cell, an organic EL (electroluminescence) element, or an optical sensor has been conventionally developed.
The photoelectric conversion element has a photoelectric conversion layer, a cathode electrode arranged on one surface of the photoelectric conversion layer, and an anode electrode arranged on the other surface of the photoelectric conversion layer. As this anode electrode, an indium-tin oxide (ITO) film is generally used. As the cathode electrode, aluminum (Al), which has a small work function, or a magnesium alloy (Mg), which has a smaller work function than Al, is used.
A photoelectric conversion element is disclosed, which uses the ITO film as a cathode electrode and a metal having a large work function as an anode electrode
As an inexpensive, stable, and flexible transparent electrode, a carbon nanotube is disclosed. Such an electrode does not use indium (In), which is a rare metal to be used in the aforementioned ITO film. Carbon nanotube films which have an unsubstituted graphene structure or planar graphene thin films are used as transparent electrodes.